1. Field of the Invention
The invention relates to a vehicle wheel suspension and, more specifically, to a spring pad positioned between a spring and spring plate.
2. Description of Related Art
Motor vehicles typically have a wheel suspension system reducing oscillation transmission from a road surface to the vehicle occupants. Such suspension systems often have one or more shock absorbers, suspension struts or springs and combinations thereof. A helical spring with a purely axial force action is one type of spring used in vehicle suspensions. There are special helical springs that, besides producing tensile or pressing forces in an axial direction, produce forces in a lateral direction. For example, such springs are used with McPherson suspension struts to reduce friction on the sliding guides of the shock absorber by using force acting in a lateral direction of the helical spring. Lateral force action can also be achieved using a lower spring plate, not fitted concentrically relative to the suspension strut against which the helical spring on the suspension strut is supported, but instead with a lateral offset on the suspension strut.
Spring plates are used with helical springs to insure a correct fit of the terminal winding of the helical spring. Generally, the spring plate carries out an outer or inner centering of the spring end of the respective helical spring. Depending on whether the helical spring is constructed with a spring end, applied in a planar manner or a pitch end, a respective receiving region may also be constructed in the spring plate for this purpose. One problem is the accumulation of moisture and deposits of dirt in the support region of the helical spring. Because accumulations of dirt and moisture in this region lead to damage to a painted surface of the respective helical spring when the helical spring moves on the spring plate, increasing the risk of corrosion and spring fractures. Spring pads of a plastic material, conventionally formed of an elastomer material, are used to insulate the helical spring from the spring plate.
Generally, spring pads are not optimally adapted to the force distribution brought about by the geometry of the terminal winding which does not extend in a homogeneous manner in the peripheral direction of the winding. Partial overloads of the elastomer material may occur such that the resilient properties thereof become worse, often during operation of the vehicle, and lead to noises commonly perceived to be unpleasant by the vehicle occupants. The original action of force of the helical spring, determined by the configuration of the wheel suspension, for example a purely axial force action, cannot be maintained during operation.